Ashless anti-rust additives

ABSTRACT

Para hydrocarbyl-substituted phenol or thiophenol dicarboxylic acids as anti-rust and anti-corrosion additives to liquid hydrocarbon fuels and lubricants.

United States Patent 119 Strang et al.

[54] 'ASHLESS ANTI-RUST ADDITIVES [75] Inventors: Aart Strang; Bernard R. Talens,

both of Amsterdam, Netherlands [73] Assignee: Shell Oil Company, New York, [22] Filed: Aug. 28, 1970 I [21] App]. No.: 68,039

[30] Foreign Application Priority Data I Sept. 10, 1969 Great Britain .44,633/69 [52] US. Cl. ..252/57, 252/486, 252/396, 44/70, 44/76 [51] Int. Cl. ..Cl0m l/20,C10m 1/38 [58] Field of Search 252/57, 396; 44/70 [56] References Cited uN'iTED STATES PATENTS 2,835,635 5/1958 Mayhew et al. ..252/57 FOREIGN PATENTS OR APPLICATIONS 809,198 2/1959 Great Britain ..252/57 Primary ExaminerDaniel E. Wyman Assistant EXaminerW. Cannon Attorney-Howard M. Floumoy and Glen R. Gru newald [5 7] ABSTRACT Para hydrocarbyl-substituted phenol or thiophenol dicarboxylic acids as anti-rust and anti-corrosion additives to liquid hydrocarbon fuels and lubricants.

4 Claims, No Drawings BACKGROUND OF THE INVENTION Known anti-rust additives for oils may be divided functionally into two groups:

1. those which neutralize the acids present in the oil; and

2. those which form a thin layer on a metal surface, thus protecting it against the action of corrosive agents.

Additives of the first group usually contain metal atoms and they are quickly depleted and therefore must be applied in rather high concentrations. Particularly when these additives are incorporated in lubricant oils that are used as motor oils in internal combustion engines. The high concentration and metal content are disadvantageous because they form ash. Additives of the second group, which are less readily depleted, can

be applied in lower concentrations. Moreover, they do not form ash.

THE INVENTION HOOC wherein X is OH or SH, R is a straight or branched chain, cyclic or acyclic, alkyl, aryl or alkaryl hydrocarbyl group having from about six to 24 carbon atoms;

and each R may be hydrogen or a hydrocarbyl group having less than 24 carbon atoms. These acids have good solubility in hydrocarbon oils, are excellent rust inhibitors and show only a slight copper-lead corrosion. The liquid hydrocarbons,'such as fuels or lubricating oil compositions, contain a minor proportion of one or more of the aromatic dicarboxylic acids of the above formula. The present compounds maybe utilized as anti-rust additives for mineral and synthetic lubricating oils which are employed as motor oils in internal combustion engines. Mineral oils that are generally paraffinic and/or naphthenic are preferred, although they may. contain substantial proportions of aromatic hydrocarbons, a single neutral base or a mixture or blend of base stocks or a bright stock may be used as the base stock. Any suitable high-viscosity index or middle viscosity index base stock or mixtures thereof can be used. However, with the use of a suitable viscosity index (VI) improver oils of somewhat lower VI as for example 65 or less may also be used. The compounds according to the invention may also be utilized as anti-rust additives in distillate or residual hydrocarbon fuels and have been found especially effective when used in gasolines. The additives of this invention are useful in leaded or unleaded gasoline compositions.

In the additives of this invention, X is preferably a hydroxyl group. Especially suitable additives are 2- hydroxybenzene-l,3-dicarboxylic acids in which both of the R, substituents are hydrogen atoms. R is preferably an aliphatic hydrocarbon group having more than 12 carbon atoms. For example, a preferred additive is 2-hydroxy-5-cetyl-benzene-l,3-dicarboxylic acid, 2-hydroxyl-5-lauryl-benzenel -3-dicarboxylic acid, 2-hydroxy-5-stearyl-benzene, l-3-dicarboxylic acid, 2-hydroxy-5-cetyl-benzenel ,3-dicarboxylic acid.

2-hydroxybenzene-l,3-dicarboxylic acids having an aliphatic hydrocarbon substituent attached to the benzene nucleus in para position relative to the hydroxyl group may be prepared by alkylation of phenol followed by phenation, carboxylation and hydrolysis. The presence of a hydrocarbon substituent. attached to the benzene nucleus in para position relative to the hydroxyl group is an essential feature of the present invention, and the alkylation is therefore carried out with an alkylation agent for phenol that attacks the benzene nucleus preferentially in a position para to the hydroxyl group.

Examples of such agents are monoolefins, which are branched at one or both of the carbon atoms adjacent to the double bond, such as tetra-isobutene and higher polyisobutenes, or precursors of these olefins, such as monohydroxy alkanes in which the hydroxyl group is attached to a tertiary carbon atom or to a carbon atom that is in an alpha-position relative to a tertiary carbon atom in the molecule. Further examples of suitable alkylation agents are l-methylcyclohexene and the product obtained by alkylation of ortho-cresol with cetene-l followed by hydrogenation of the alkylate.

When the aromatic dicarboxylic acids according to the invention are used as anti-rust additives in lubricants or fuels, their concentrations can vary within wide limits. The additives are preferably added in an amount from about 0.01 to about 5.0 percent w, especially from 0.05 to 1.0 percent w.

In addition to the present acids, lubricants or fuel compositions can contain other additives. For example, if the acids are added to a lubricant, the latter may also contain anti-oxidants, extreme pressure agents, antiwear agents, viscosity-index improvers, thickeners, dispersants, anti-foam agents and other substances known'in the art to perform a particular function or functions provided they are otherwise compatible.

EXAMPLEI Preparation of 2-I-Iydroxy-5 -ce tylbenzene 1 ,3-dicarboxylic acid (Compound I) A mixture of orthoand para-cetylphenol obtained by alkylation of phenol with cetene-l was subjected to;

EXAMPLE I] To determine the anti-rust properties of compounds according to the invention in a lubricating oil, Compound I was compared with five commercial anti-rust additives (Compounds AE) in a laboratory corrosion test. In this test the corrosion is measured continuously by recording the change in the resistance of a standard iron wire (0.1 mm) immersed in an emulsion of a lubricating oil in which the anti-rust additive concerned has been incorporated. The lubricating oil emulsion is prepared by emulsifying an SAE oil containing 7.5 percent w of commercial viscosity index (VI) improver, 0.75 percent w of a commercial anti-oxidant and l percent w of a commercial anti-scuffing agent with 5 percent w of a synthetic water phase. The synthetic water phase which is representative of the water phase in an engine contains 0.6 N HCl, 0.3 N Al(NO and 0.1 N (NH.,)2SO? The test conditions of this laboratory corrosion test closely resemble but are much more severe than those prevailing in an ordinary engine.

The results of these tests are summarized in Table I.

Table I Compound Composition Corrosion rate, mm/year at a concentration of l 2-hydroxy-5-cetylbenzene- 0.05

l,3-dicarboxylic acid A calcium naphtha sulphonate 0. l 5( l%) B phosphoric esters 0.1 0.1 C superbasic magnesium salt 0.] 0.0l D tetrachlorophthalic acid 0.3 L2 E dodecenyl succinic acid 0.5 0.4

Reference oil without anti-rust additives 0.5 0.7

It may be seen from Table I that the additive of this invention even in very low concentrations is more effective as a rust inhibitor than other commercial preparations used for this purpose.

EXAMPLE III Since only compounds I, B and C were adequate as rust inhibitors in Example II. These compounds were tested to determine their corrosivity toward lead and copper, two common bearing materials. In the test 0.1 percent w of the indicated compound was added to the same reference oil under identical conditions and the corrosivity of each composition was measured as loss of weight of the copper and lead specimens immersed in the oil. The reference oil alone was of course substantially non-corrosive, but it was otherwise unsuitable because it was not rust inhibited.

The results of these tests are summarized in Table I1.

anti-rust additives 0 EXAMPLE 1v Since composition B proved too corrosive toward lead it was unsuitable and compositions I and C were further tested. The further tests involved employing oil rust-inhibited with compositions I and C in a Ford-Anglia engine operated at constant speed (2,000 rpm) and constant power (6 bhp) for 24 hours, while the top cover of the engine was cooled to 45C to promote condensation of the blow-by gases. The degree or rate of corrosion in these tests was assessed by:

l. the loss in weight of the push rods;

2. the loss in weight of new mild-steel test plates in the top-cover area; and

3. the loss of weight of the dipstick.

The results of the motor tests are summarized in Table III.

Table III Composition Concentration Loss in weight, mg, of

no. 0W

test push dipstick plates rods 1 0.05 35 i5 6 l 0.0 28 14 l C 0.025 91 26 21 C 0.5 72 14 0 Reference oil without anti-rust additives l34 218 41 In addition to being more corrosive, composition C is an ashforrning composition that has the above-men- HOOC GOOH wherein X is OH, R is an alkyl group of between more than 12 and 24 carbon atoms, and each R is hydrogen.

2. The composition of claim 1 wherein the lubricating oil is a mineral oil.

3. The composition of claim 2 wherein the dicarboxylic acid is 2-hydroxy-5-cetylbenzene-l,3-dicarboxylic acid.

4. The composition of claim 1 containing from about 0.01 to 5 percent w of the dicarboxylic acid. 

2. The composition of claim 1 wherein the lubricating oil is a mineral oil.
 3. The composition of claim 2 wherein the dicarboxylic acid is 2-hydroxy-5-cetylbenzene-1,3-dicarboxylic acid.
 4. The composition of claim 1 containing from about 0.01 to 5 percent w Of the dicarboxylic acid. 